Perioperative intravenous low-dose ketamine for neuropathic pain after major lower back surgery: A randomized, placebo-controlled study

Christoph Czarnetzki 1 2, Jules Desmeules 2 3, Enrico Tessitore 2 4, Antonio Faundez 5,

Jocelyne Chabert 3, Youssef Daali 2 3, Roxane Fournier 1 2, Elise Dupuis-Lozeron 6,

Christine Cedraschi 2 3, Martin Richard Tramèr Eur J Pain 2020 Mar;24(3):555-567

Abstract

Background: Chronic pain after major lower back surgery is frequent. We investigated in adults the effect of perioperative low-dose ketamine on neuropathic lower back pain, assessed by the DN4 questionnaire, 6 and 12 months after major lower back surgery.

Methods: In this single-centre randomized trial, 80 patients received intravenous ketamine 0.25 mg/kg preoperatively, followed by 0.25 mg kg-1 hr-1 intraoperatively, and 0.1 mg kg-1 hr-1 from 1 hr before the end of surgery until the end of recovery room stay; 80 controls received placebo.

Results: Preoperatively, 47.4% of patients in the ketamine group and 46.3% in the placebo group had neuropathic pain; 10% and 3.8%, respectively, were using strong opioids. At the end of the infusion, the median cumulative dose of ketamine was 84.8 mg (IQR 67.4-106.7) and the median plasma level was 97 ng/ml (IQR 77.9-128.0). At 6 months, 28.8% of patients in the ketamine group and 23.5% in the placebo group had neuropathic pain (absolute difference, 5.2%; 95% CI -10.7 to 21.1; p = .607). At 12 months, 26.4% of patients in the ketamine group and 17.9% in the placebo group had neuropathic pain (absolute difference 8.5%; 95% CI -6.7 to 23.6; p = .319).

Conclusions: In this patient population with a high prevalence of neuropathic lower back pain undergoing major lower back surgery, a perioperative intravenous low-dose ketamine infusion did not have an effect on the prevalence of neuropathic lower back pain at 6 or 12 months postoperatively.

Significance: We were unable to show any analgesic benefit of a short-term perioperative ketamine infusion as an adjuvant to multimodal analgesia in patients with a high prevalence of neuropathic lower back pain undergoing major back surgery. Based on these data, the widespread opinion that ketamine is universally analgesic across different pain conditions must be challenged.